A variety of techniques are available for providing visual displays of graphical, textual or video images to a user. For example, cathode ray tube displays ("CRTs"), such as televisions and computer monitors, are very common. Such devices suffer from several limitations. For example, CRTs are typically bulky, consume substantial amounts of power and require high voltages, making them undesirable for portable or head-mounted applications.
Flat panel displays, such as liquid crystal displays, plasma displays, and field emission displays, may be less bulky and consume less power. However, typical flat panel displays utilize screens that are several inches across. Such screens have limited use in head mounted applications or in applications where the display is intended to occupy only a small portion of a user's field of view.
More recently, very small displays have been developed for partial or augmented view applications and for various head-mounted applications. In augmented view applications, a portion of the display is positioned in the user's field of view and presents an image that occupies a small region 42 of the user's field of view 44, as shown in FIG. 1. The user can thus see both a displayed image 46 and background information 48.
One approach to providing a small display is a scanned beam display such as that described in U.S. Pat. No. 5,596,339 to Furness, et. al., entitled "VIRTUAL RETINAL DISPLAY WITH FIBER OPTIC POINT SOURCE," which is incorporated herein by reference. In such displays, a modulated beam of light is scanned through a periodic two-dimensional pattern. The scanned light is then received by a viewer's eye. The light strikes the viewer's retina and the viewer perceives an image in response.